Explanation:

 The Kalka–Shimla railway is a 2 ft 6 in (762 mm) narrow-gauge railway in North India which traverses a mostly-mountainous route from Kalka to Shimla. It is known for dramatic views of the hills and surrounding villages. The railway was built in 1898 to connect Shimla, the summer capital of India during the British Raj, with the rest of the Indian rail system. During its construction, 107 tunnels and 864 bridges were built along the route. The project's chief engineer was H. S. Harington.